1. Field of the Invention
The present invention relates to guide catheters and diagnostic catheters used in medical catheterization procedures. In particular, the present invention relates to an improved guide or diagnostic catheter having a simple, braid-free catheter design, which is capable of performing the functions of conventional diagnostic and guide catheters.
2. Description of the Prior Art
Guide catheters and diagnostic catheters are well known for use in coronary catheterization and percutaneous transluminal coronary angioplasty (PTCA) procedures. Guide catheters aid in treatment of arterial lesions by providing a conduit for positioning dilatation balloon systems across an arterial stenosis. Guide catheters and diagnostic catheters work with various assemblies for performing other medical, therapeutic, and diagnostic procedures, such as dye delivery, arterial flushing, or arterial pressure monitoring.
Diagnostic catheters are used during cardiac catheterization for diagnosis of coronary artery disease in order to define vessel anatomy, isolate lesions, and identify adjacent cardiac branches which may impinge on the lesion and affect ventricular function.
For diagnosis of the coronary artery, the femoral artery is entered percutaneously and a sheath is inserted into the artery to provide access to the patient's vascular system. The diagnostic catheter is inserted into the femoral artery through this introducer sheath over a guide wire and advanced up the aorta to the aortic arch. Once over the aortic arch, the guide wire may be removed. A Y-adapter and manifold assembly are attached to the diagnostic catheter for implementation of diagnostic procedures, such as dye delivery, flushing capabilities, and arterial pressure monitoring.
The diagnostic catheter design generally includes a shaft having a proximal and a distal end. A lumen extends longitudinally through the shaft from the proximal to the distal end. Operably connected to the proximal end of the shaft is a hub assembly, for connection to catheterization equipment, and connected to the distal end of the shaft is a soft tip.
The distal end of the guide catheter shaft is shaped to access the ostium of the coronary artery having the stenotic lesion. Different shapes may be employed for access to the ostium of a right or left coronary artery, mammary artery or the ostium of a bi-pass vein. During the diagnosis procedure, the physician advances and maneuvers the diagnostic catheter shaft within the artery, while at the same time injecting dye. The physician observes the dye using an angiography monitor for visualization of the patient's coronary system.
The diagnostic catheter is advanced and maneuvered until the distal end is properly engaged in the ostium of the coronary artery the physician believes to contain the stenosis. Once seated in the ostium, the physician injects additional dye for observations of obstruction to dye flow, indicative of the coronary disease.
For treatment of the coronary disease through angioplasty or other catheter based treatments, guide catheters are used. The guide catheters provide access to the area within the arterial system containing the stenotic lesion, and support for the treatment catheter which often includes a balloon dilatation system. Guide catheters similar in construction to diagnostic catheters, although they are generally larger in size. Prior art guide catheters typically have a pre-shaped distal section or tip region to aid in access to the ostium of the coronary artery to receive treatment.
In operation, the guide catheter is introduced over a guide wire through a previously placed femoral introducer sheath and advanced up to the aortic arch. The guide wire can then be removed, and the guide catheter can be advanced and maneuvered until the guide catheter soft tip is properly engaged in the ostium of the coronary artery to be dilatated. A Y-adapter and manifold assembly are attached to the guide catheter hub at the proximal end for implementation of therapeutic procedures, such as dye delivery, flushing capabilities, pressure monitoring and delivery of the dilatation balloon system.
Diagnostic catheters and guide catheters are manufactured in hundreds of shapes and curve styles to accommodate anatomical variances in humans and to access specific areas within the coronary system. Curve shapes are also designed to provide support against the aortic wall when seated within the ostium, to resist the tendency for a catheter to "pop out" of the ostium (termed backout force) when injecting dye or advancing a treatment catheter into the artery. Catheters are presently specifically manufactured with high curve retention to maintain catheter placement within the ostium and to resist backout forces.
During angioplasty procedures, the catheters must be able to traverse tortuous pathways through blood vessels to the stenosis in a manner as atraumatic as possible. Therefore, to limit insertion time and discomfort to the patient, the catheter must be stiff enough to resist the formation of kinks, while at the same time the catheter must possess flexibility to be responsive to maneuvering forces when guiding the catheter through the vascular system. It is important that the guide catheter exhibit good torque control such that manipulation of a proximal portion of the guide catheter is responsively translated to the tip or distal end of the catheter to curve and guide the catheter through the tortuous pathways.
To meet the above performance requirements, guide catheters and diagnostic catheters are manufactured using polymers in conjunction with a braid of high-strength fibers or stainless steel wires incorporated into the tube. The guide catheters are generally formed of three layers: a first inner layer commonly formed of polytetrafluoroethylene to decrease the coefficient of friction between a balloon catheter and the guide catheter; a middle layer consisting of braided wire for torque control; and a third, outer layer commonly formed of polyethylene, polyurethane, polyether blocked amide (PEBA) or a nylon-blend for stable positioning of the guide catheter, and providing backout support during other treatment procedures.
During diagnostic and therapeutic procedures, it is often necessary to use more than one shaped or curved catheter to access the right coronary, left coronary, mammary artery, or bipass vein for visualization of each vessel. The procedure of exchanging diagnostic catheters for visualization of different vessels requires more procedural time and exposes the patient to extended x-ray time and fluoroscopy. Additionally, hospitals are required to inventory hundreds of catheters with various curves, tip shapes and diameters to accommodate the various procedures for each patient.
It is desirable in catheter design for the inside diameter of the diagnostic or guide catheter to be maximized relative to the outside diameter, providing maximum space for dye flow and dilatation catheter delivery. While designing catheters to meet these design goals, the catheters must continue to meet performance requirements of burst pressure requirements, kink resistance, curve retention, column strength, and torque control for advancement within the patient's vascular system.